Debt Ratio Calculator

Lenders use your gross monthly income as the denominator and add every recurring required payment in the numerator. That includes your full housing payment (mortgage principal, interest, property taxes, homeowners insurance, HOA, plus PMI when applicable, often abbreviated PITI), every car loan or lease payment, the minimum payment on each credit card, student loans, personal loans, and court-ordered obligations like child support or alimony. Utilities, groceries, gas, health insurance premiums outside the housing PITI, and discretionary spending do not count. Lenders pull most figures straight from your credit report, so the minimum payment that appears on the report is what ends up in the ratio, not the larger amount you typically pay each month.

Conventional mortgages backed by Fannie Mae and Freddie Mac follow a 28/36 guideline: housing PITI should stay at or below 28% of gross monthly income (front-end ratio) and total monthly debt at or below 36% (back-end ratio). FHA loans, which are insured by the Federal Housing Administration and aimed at lower-down-payment borrowers, run a more generous 31/43 rule. FHA underwriters routinely approve back-end ratios in the 43% to 50% band when other compensating factors look strong (high credit score, large cash reserves, or low loan-to-value). The trade-off is FHA mortgage insurance premiums, which last for the life of the loan when the down payment is under 10%.

In January 2014 the Consumer Financial Protection Bureau (CFPB) implemented the Ability-to-Repay and Qualified Mortgage (QM) rules under the Dodd-Frank Act. A Qualified Mortgage gives the lender a safe harbor against lawsuits claiming the borrower could not afford the loan, but only when the borrower's back-end DTI is at or below 43%. The 43% threshold became the de facto industry red line for most prime mortgages. The 2021 CFPB amendment replaced the strict 43% cap with a price-based test for many conventional QMs, but in practice most mainstream lenders still treat 43% as the upper bound and reserve approvals above it for FHA, VA, USDA, or non-QM jumbo programs.

Both matter, but the back-end ratio decides most mortgage approvals. The front-end ratio (housing only) checks whether the proposed mortgage payment alone is sustainable. The back-end ratio (housing plus every other recurring debt) checks whether the full obligation load is sustainable. A borrower can pass the 28% front-end test on a generous income and still fail the 36% back-end test because a car loan and student loans push the combined number too high. The opposite is rare in practice. When the two ratios disagree, lenders almost always defer to the back-end number because it captures the full cash-flow picture.

You only have two levers: shrink the numerator (monthly debt) or grow the denominator (gross income). On the debt side, paying off the smallest balance entirely removes its minimum payment from the ratio (which is why the debt snowball helps DTI faster than the avalanche). Refinancing a high-rate car loan or consolidating credit card debt into a lower fixed payment also drops the number. Avoid taking on any new credit in the 90 days before applying; a hard pull plus a new auto loan can move your DTI several points overnight. On the income side, lenders count overtime, bonuses, and side income only when there is a documented two-year history, so do not assume a recent raise will fully apply. If you are close to the cap, increasing your down payment is often the fastest fix because a smaller loan shrinks the housing PITI directly.